Minimization of ACL Storage by Adding Minimal Hardware of Range Matching and Logical Gates to TCAM

Ternary Content Addressable Memory (TCAM) is a special type of memory used in routers in order to achieve high speed packet classification. The classification is performed using the five fields in an Access Control List (ACL), port numbers being one of them. Since port numbers that are expressed in ranges require multiple entries in storage, this results in an increased cost of hardware. In this paper, the authors propose a method to reduce the number of entries when expressing ranges in TCAM. They use Range Matching Devices integrated within the TCAM's control logic and optimized prefix expansion that utilizes logical AND and NOT gates in the TCAM array itself.